11 research outputs found
Supplementary data for the article: Guan, J.; Wriglesworth, A.; Sun, X. Z.; Brothers, E. N.; ZariÄ, S. D.; Evans, M. E.; Jones, W. D.; Towrie, M.; Hall, M. B.; George, M. W. Probing the Carbon-Hydrogen Activation of Alkanes Following Photolysis of Tpâ˛Rh(CNR)(Carbodiimide): A Computational and Time-Resolved Infrared Spectroscopic Study. Journal of the American Chemical Society 2018, 140 (5), 1842â1854. https://doi.org/10.1021/jacs.7b12152
Peer-reviewed manuscript: [http://cherry.chem.bg.ac.rs/handle/123456789/2893]Related to published version: [http://cherry.chem.bg.ac.rs/handle/123456789/2091]Related to accepted version: [http://cherry.chem.bg.ac.rs/handle/123456789/2893
Supplementary data for the article: Pitts, A. L.; Wriglesworth, A.; Sun, X.-Z.; Calladine, J. A.; ZariÄ, S. D.; George, M. W.; Hall, M. B. Carbon-Hydrogen Activation of Cycloalkanes by Cyclopentadienylcarbonylrhodium-A Lifetime Enigma. Journal of the American Chemical Society 2014, 136 (24), 8614â8625. https://doi.org/10.1021/ja5014773
Supplementary material for: [https://doi.org/10.1021/ja5014773]Related to published version: [http://cherry.chem.bg.ac.rs/handle/123456789/1792
Calculating singlet excited states: comparison with fast time-resolved infrared spectroscopy of coumarins
In contrast to the ground state, the calculation of the infrared (IR) spectroscopy of molecular singlet excited states represents a substantial challenge. Here we use the structural IR fingerprint of the singlet excited states of a range of coumarin dyes to assess the accuracy of density functional theory based methods for the calculation of excited state IR spectroscopy. It is shown that excited state Kohn-Sham density functional theory provides a high level of accuracy and represents an alternative approach to time-dependent density functional theory for simulating the IR spectroscopy of the singlet excited states
Supplementary data for the article: Guan, J.; Wriglesworth, A.; Sun, X. Z.; Brothers, E. N.; ZariÄ, S. D.; Evans, M. E.; Jones, W. D.; Towrie, M.; Hall, M. B.; George, M. W. Probing the Carbon-Hydrogen Activation of Alkanes Following Photolysis of Tpâ˛Rh(CNR)(Carbodiimide): A Computational and Time-Resolved Infrared Spectroscopic Study. Journal of the American Chemical Society 2018, 140 (5), 1842â1854. https://doi.org/10.1021/jacs.7b12152
Peer-reviewed manuscript: [http://cherry.chem.bg.ac.rs/handle/123456789/2893]Related to published version: [http://cherry.chem.bg.ac.rs/handle/123456789/2091]Related to accepted version: [http://cherry.chem.bg.ac.rs/handle/123456789/2893
Influence of molecular design on radical spin multiplicity: characterisation of BODIPY dyad and triad radical anions
This journal is Š the Owner Societies. A strategy to create organic molecules with high degrees of radical spin multiplicity is reported in which molecular design is correlated with the behaviour of radical anions in a series of BODIPY dyads. Upon reduction of each BODIPY moiety radical anions are formed which are shown to have different spin multiplicities by electron paramagnetic resonance (EPR) spectroscopy and distinct profiles in their cyclic voltammograms and UV-visible spectra. The relationship between structure and multiplicity is demonstrated showing that the balance between singlet, biradical or triplet states in the dyads depends on relative orientation and connectivity of the BODIPY groups. The strategy is applied to the synthesis of a BODIPY triad which adopts an unusual quartet state upon reduction to its radical trianion
Carbon-Hydrogen Activation of Cycloalkanes by Cyclopentadienylcarbonylrhodium-A Lifetime Enigma
Carbon-hydrogen bond activation reactions of four cycloalkanes (C5H10, C6H12, C7H14, and C8H16) by the Cp'Rh(CO) fragments (Cp' = eta(5)-C5H5 (Cp) or eta(5)-C5Me5 (Cp*)) were modeled theoretically by combining density functional and coupled cluster theories, and their reaction rates were measured by fast time-resolved infrared spectroscopy. The reaction has two steps, starting with the formation of a a-complex intermediate, followed by oxidative addition of the C-H bond by the rhodium. A range of a-complex stabilities among the electronically unique C-H bonds in a cycloalkane were calculated and are related to the individual strengths of the C-H bond's interactions with the Rh fragment and the steric repulsion that is incurred upon forming the specific a-complex. The unexpectedly large increase in the lifetimes of the a-complexes from cyclohexane to cycloheptane was predicted to be due to the large range of stabilities of the different sigma-complexes found for cycloheptane.. The reaction lifetimes were simulated with two mechanisms, with and without migrations among the different complexes, to determine if ring migrations prior to C-H activation were influencing the rate. Both mechanisms predicted similar lifetimes for cyclopentane, cyclohexane, and, to a lesser extent, cycloheptane, suggesting ring migrations do not have a large impact on the rate of C-H activation for these cycloalkanes. For cyclooctane, the inclusion of ring migrations in the reaction mechanism led to a more accurate prediction of the lifetime, indicating that ring migrations did have an effect on the rate of C-H activation for this alkane, and that migration among the a-complexes is faster than the C-H activation for this larger cycloalkane.Supplementary material: [http://cherry.chem.bg.ac.rs/handle/123456789/3685
CarbonâHydrogen Activation of Cycloalkanes by Cyclopentadienylcarbonylrhodiumî¸A Lifetime Enigma
Carbonâhydrogen
bond activation reactions of four cycloalkanes
(C<sub>5</sub>H<sub>10</sub>, C<sub>6</sub>H<sub>12</sub>, C<sub>7</sub>H<sub>14</sub>, and C<sub>8</sub>H<sub>16</sub>) by the Cpâ˛RhÂ(CO)
fragments (CpⲠ= Ρ<sup>5</sup>-C<sub>5</sub>H<sub>5</sub> (Cp) or Ρ<sup>5</sup>-C<sub>5</sub>Me<sub>5</sub> (Cp*)) were
modeled theoretically by combining density functional and coupled
cluster theories, and their reaction rates were measured by fast time-resolved
infrared spectroscopy. The reaction has two steps, starting with the
formation of a Ď-complex intermediate, followed by oxidative
addition of the CâH bond by the rhodium. A range of Ď-complex
stabilities among the electronically unique CâH bonds in a
cycloalkane were calculated and are related to the individual strengths
of the CâH bondâs interactions with the Rh fragment
and the steric repulsion that is incurred upon forming the specific
Ď-complex. The unexpectedly large increase in the lifetimes
of the Ď-complexes from cyclohexane to cycloheptane was predicted
to be due to the large range of stabilities of the different Ď-complexes
found for cycloheptane. The reaction lifetimes were simulated with
two mechanisms, with and without migrations among the different Ď-complexes,
to determine if ring migrations prior to CâH activation were
influencing the rate. Both mechanisms predicted similar lifetimes
for cyclopentane, cyclohexane, and, to a lesser extent, cycloheptane,
suggesting ring migrations do not have a large impact on the rate
of CâH activation for these cycloalkanes. For cyclooctane,
the inclusion of ring migrations in the reaction mechanism led to
a more accurate prediction of the lifetime, indicating that ring migrations
did have an effect on the rate of CâH activation for this alkane,
and that migration among the Ď-complexes is faster than the
CâH activation for this larger cycloalkane
Influence of molecular design on radical spin multiplicity: characterisation of BODIPY dyad and triad radical anions
A strategy to create organic molecules with high degrees of radical spin multiplicity is reported in which molecular design is correlated with the behaviour of radical anions in a series of BODIPY dyads. Upon reduction of each BODIPY moiety radical anions are formed which are shown to have different spin multiplicities by electron paramagnetic resonance (EPR) spectroscopy and distinct profiles in their cyclic voltammograms and UV-visible spectra. The relationship between structure and multiplicity is demonstrated showing that the balance between singlet, biradical or triplet states in the dyads depends on relative orientation and connectivity of the BODIPY groups. The strategy is applied to the synthesis of a BODIPY triad which adopts an unusual quartet state upon reduction to its radical trianion